Divider ob compass



UNITED STATES PATENT Brion. w

D. H. OHAMBERLAINOF BOSTON, MASSACHUSETTS, ASSIGNOR To HOMERS & LADD, OF

BOSTON, MASSACHUSETTS.

DIVIDER OR COMPASS.

Specification of Letters Patent No. 7,257, dated April 9, 1850.

To all whom @'25 may concern Be it known that I, DEXTER H. YCHAMBER LAIN, of Boston, in the county of Suolk and State of Massachusetts, haveinvented certain new and useful Improvements in Dividers or Compasses, and that the following description, taken in connection with the accompanying drawings,`hereinafter referred to, forms a full and exact specication of the same, wherein I have set forth the nature and principles of my saidv improvements by which my invention may be distinguished from others of a similar class, together with such parts as I claim and de sire to have secured tome by Letters Patent.

. The figures of the accompanying plate of drawings represent my improvements. Fgure l is a front elevation of my improved dividers. Fig.`2 is an elevation of one side. Fig. 3 is an elevation of the opposite side. Fig. 4L is a plan or top view as they would appear looking down vertically upon them, and Fig. 5 is a similar view with the dividers inverted.

The distinguishing feature in my improved dividers, consists in the adaptation of what ,is called a micrometer adjustment of a peculiar kind, to one of the legs, by which it may be moved with regularity a little distance, as is often very desirable among machinists and oiners, where the radius of any specific or determined arc or circle is to be used.

The construction of my improved compasses is as follows: a a and b b are the two legs, jointed or hinged together in the usual way. Each of these legs has a slot cut through it (as shown by dotted lines in Fig. l) and in Figs. 2 and 4, in which the circular rack bar c c is arranged as represented. This rack bar turns a little at one end on a pin Z passed through it and both sides of the slots in the leg a' a, and this slot and that in the leg Zn b is so mortised out as to allow sufficient play in a vertical plane to the rack bar in order to disengage it or throw it out o-f gear, from the micrometer screw e, which is connected to the leg b b, by the pin or rivet f Fig. 3, on which it turns, and having a milled head g, by which it is turned.

IIn the slot of the leg I) b above the rack bar o a bent spring h is fitted so as to keep the teeth of the Said bar in gear with the threads of the micrometer screw, but when it is desired to move the leg b Z) any considerable distance, this bar may be drawn away from the screw with one hand while with the other the leg may be set any distance at pleasure.

Having thus described my improvements I Shall state my claim asfollows.

What I claim as my invention and desire to have secured to me by Letters Patent is,

Making dividers or Compasses with the micrometer adjustment herein above described, the combination of devices for the same, consisting of a circular rack bar arranged in slots in the legs of the divider, with a spring in the slot of the movable leg Z) b, and the micrometer screw, all work-` ing together as hereinabove specied.

D. I-I. CHAMBERLAIN.

Witnesses:

EZRA LINCOLN, Jr., Granny J. F. BRYANT. 

